Air cylinder



K. A. DOUTT AIR CYLINDER June 26, 1956 Filed May 6, 1953 ATTQR/VEY United States Patent Am CYLINDER Kingsley A. Doutt, Alpena, Mich., assigner to Petch Manufacturing Company, Alpena, Mich., a corporation of Michigan Application May 6, 1953, Serial No. 353,280

4 Claims. (Cl. 121-38) This invention relates to an air cylinder and more particularly to an improved air cushioning structure for an air cylinder.

The principal object of the invention is the provision of a tioating cushion construction for air cylinders and an improved needle valve control therefor.

A further object of the invention is the provision of an improved needle valve control for an air cylinder construction whereby the range of eiective adjustment is materially increased.

A still further object of the invention is the provision or an improved air cylinder construction including a replaceable oating cushion bushing which is self-aligning with the piston rod of the air cylinder.

A further object of the invention is the provision of an air cylinder construction including a oating cushion bushing movably mounted in the cylinder assembly for selfalignment with the piston rod whereby the service life and functioning of the cushion is greatly improved.

The air cylinder construction disclosed herein and more specifically the improvements in said construction which relate to the ioating cushion bushing and the control valves of the cylinder contribute materially to the improved product primarily in that longer, more satisfactory life of the cushioning portions of the structure is obtained through the use of a floating cushion bushing which is self-aligning with the piston rod and, therefore, capable of adjusting itself to the peculiarities of the rod.

The control valve construction disclosed relates to the control valves used in the cushioning structures of the air cylinder assembly, as the control of the flow of the fluid results in the self-cushioning of the piston at its opposite ends of travel. The control valves are so formed that they act as spindle valves as well as needle valves and thereby contribute to the efficiency of the cushioning arrangement provided.

With the foregoing and other objects in view which will appear as the description proceeds, the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it being the intention to cover all changes and modifications f the example of the invention herein chosen for purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention.

The invention is illustrated in the accompanying drawing, wherein:

Figure l is an end View of an air cylinder formed in accordance with the invention.

Figure 2 is a vertical section taken on line 2-2 of Figure l.

By referring to the drawings and Figure 2 in particular it will be seen that the air cylinder disclosed is formed of a pair of spaced end castings and 11 having an intermediate barrel 12, the ends of the barrel 12 being engaged upon annular shoulders 13 and 14 of the end castings 10 and 11 and provided with sealing glands comice prising O rings 15 and 16 positioned in annular recesses 17 and 18 formed in the castings 10 and 11.

Tie rods 19-19 extend in parallel relation to the barrel 12 and through oppositely disposed apertures in the end castings 10 and 11, the outermost ends of the tie rods 19 being threaded and provided with fasteners 20-20 whereby the end castings and barrel are held in assembled relation.

The rod end of the air cylinder as illustrated in Figure 2 of the drawings is provided with a rod end ange 21 which in turn is apertured as at 22 for the mounting of the air cylinder. The end casting 10 and the rod end ilange 21 are apertured for the reception of a piston rod 23, The innermost end portion 24 of the piston rod 23 is of smaller diameter than the remainder thereof and provided with an annular semi-conical end 25 adapted for self-registry with a floating bushing 26 which is in turn loosely positioned in the end casting 11 and sealed with respect thereto by an 0 ring 27 and retained in position by a snap ring 28. A portion of the rod 23 inwardly from the end 24 is threaded as at 29 and receives a nut 30 which serves to mount a three-part piston 31.

The outer parts of the three-part piston 3i are provided with piston sealing cups 32 and the three-part piston assembly is mounted on the piston rod 23 between the nut 3) and an annular band 33 which is mounted on the piston rod 23 adjacent a shoulder 34. The annular band 33 has a tapered outer end portion 35 which registers with a bushing 36 positioned in the end casting 1i) and sealed with respect thereto by an O ring 37 and retained in position therein by a snap ring 33.

A gland 39 is also positioned in the end casting 10 about the piston 34 and retained by a ring 40 which in turn is secured to the end casting 10 by a plurality of fasteners 41. The end casting 10 has a port 42 communieating with an annular chamber 43 surrounding the piston rod 23 and a by-pass passageway 4d establishes cornmunication between the annular chamber 43 and the chamber defined by the barrel 12.

A combination spindle and needle valve 45 is positioned in a portion of the by-pass passageway 44 and so formed that a spindle valving action with respect to the passageway 44 occurs piror to the seating of the pointed or needle valve end thereof in a valve seat 46 thereby providing an unusual ilexibility of adjustment.

The combination spindle and needle valve 45 is threadably mounted in a threaded opening 47 which extends outwardly of the end casting 16 and thereby enables the adjustment of the combination spindle and needle valve from the exterior of the air cylinder. A similar combination spindle and needle valve d8 controls a by-pass passageway 49 in the end casting 11.

it will be observed that in operation the piston being at the complete inner end of travel and adjacent the end casting 11 will have engaged the end section 24 in the floating bushing 26 through which the majority of tluid passes to communicate with a port i5 in the end casting 11 thereby causing the remaining fluid between the piston 31 and the end casting 11 to tiow through the by-pass passageway 49 which is controlled by the combination spindle and needle valve 4S and thus serving to effectively cushion the piston.

Any irregularities in the alignment of the piston rod 23 are automatically compensated for by the floating bushing 26 so that there is no undue wear of the rod 23 or the bushing 36.

When the piston 31 moves to the rod end of the cylinder, the portion thereof dened by the end casting 19, movement is rapid until the band 33 enters the bushing 35 which then causes the remainder of the fluid to ilow through the by-pass passageway 44 and under the con- 3 trol of the combination spindle and needle valve 45 thus e'ecting cushioning at that end of the stroke. As the bushing 36 is located relatively close to the gland 39 and gland ring 40, there is little deviation from -normal alignment and, accordingly, a more conventional bushing may be employed with maximum wear at this point.Y

Those skilled in the art will thus recognize that an improved air cylinder construction results from the formation of the cushioning arrangement and, specically, the floating bushing 26 which automatically aligns itself with the end 24 of the rod 23 and insures cushioning action throughout the long and satisfactory life of the device.

Secondarily, the improvement relates to the formation of the combination spindle and needle valves 45 and 48 which are capable of an unusual degree of adjustment due to the fact that the body portions thereof act as spindle valves engaging the by-pass passageways 44 and 49 prior to the actual seating of the needle valves in Vthe valve seats also formed in said passageways.

It will thus be seen that the several objects of the invention are achieved by the improvements in air cylinder disclosed herein,

Having thus described my invention, what I claim is:

l. The improvement in a piston and cylinder construction wherein a self-cushioning construction is employed and including a piston and piston rod, a barrel, end castings secured to the ends of said barrel, said end castings having uid passageways therein and annular chambers merging with said uid passageways, an extenion on said piston rod beyond said piston, a circular centrally apertured rigid member positioned in said annular charnsoV ber, said passageway and annular chamber lying on a cular member when moved toward the same and acting to close said annular chamber and passageway when said piston rod extension is engaged in said aperture in said circular member.

2. The improvement in a piston and cylinder construction incorporating a self-cushioning construction as set forth in claim 1 and wherein said circular member is mounted in said annular chamber in said end casting in transversely movable relation thereto to permit self-alignment with said extension of said piston rod. Y

3. The improvement in a piston and cylinder construction set forth in claim l and wherein said circular member is movable laterally of said end casting and the annular chamber therein and immovable axially thereof, and wherein a snap ring is disposed in said annular chamber adjacent said circular member to retain the same in said annular chamber.

4. T he improvement in a piston and cylinder construction set forth in claim l wherein a by-pass passageway is formed in said end casting around said annular chamber and circular member positioned therein, and wherein a combination spindle and needle valve is positioned in said by-pass passageway said by-pass passageway including a right angle turn and said combination spindle and needle valve comprising a main portion defining said spindle and movable at right angles to one portion of said right angled passageway and wherein said needle valve comprises a pointed end on said spindle portion registrable in the other portion of said right angular by-pass passageway.

References Cited in the file of this patent UNITED STATES PATENTS 

